[adzii_nufc]

He accepted moral responsibility for his part in the Holocaust a long time ago, but that isn't the same thing as criminal responsibility. If what he did was considered to have facilitated the Holocaust, are prisoners who carried bodies out of the gas chambers also guilty of facilitating the Holocaust? Are we also going to go after individuals in the military police who enforced military discipline amongst the guards under the premise that they facilitated the Holocaust by not allowing the camps to fall into disarray? Should all members of the Wehrmacht be prosecuted as well, since the Holocaust's millions of deaths wouldn't have happened if they'd refused to invade other countries?
At some point, you have to draw a line. Groening never harmed anyone personally, never ordered or organized the harming of anyone, and his job wasn't critical to the actual process of killing. Without him and people like him, graft in the camps would increase and the Third Reich wouldn't recycle the possessions of its victims as efficiently, but tens of millions would still die.